any, a 100% orange juice fanfic

Of Metal And Mate Posted originally on the Archive of Our Own at /works/6184534.

Rating: Explicit Archive Warning: Creator Chose Not To Use Archive Warnings Category: M/M Fandom: ワンパンマン One-Punch Man Relationship: Genos/Saitama (One-Punch Man) Characters: Genos (One-Punch Man), Saitama (One-Punch Man) Additional Tags: Omegaverse, Alpha/Beta/Omega Dynamics, canonverse, Omega Genos,

Alpha Saitama, Scent Marking, Mating Cycles/In Heat, Mating, Biting, Scent Kink, This Is Probably Not The Genosai You Are Looking For, Knotting

Language: English Stats: Published: 2016-03-07 Completed: 2018-04-06 Words: 11,217 /tags/Knotting

Of Metal And Mate by sciencefictioness

Summary

Genos always hated the thought of being an omega, so when Kuseno rebuilt him out of metal and wire, he told the doctor to leave out his glands. Make him a beta, no one would know.

Then he met Saitama, and things were not so simple anymore.

Translation into Русский available: Of Metal And Mate by /users/None_for_all/pseuds/None_for_all

Omega

Genos hadn't really known what to expect when he walked back into the apartment after being stuck on Kuseno's table for days on end, but this was definitely not it. Saitama's eyes lit up alpha white, only the second time Genos ever saw them do so, before he stalked over to the door. Saitama's movements were almost predatory, and he took Genos' chin in his hand and tilted his face to the side. Shoved his nose into Genos' neck, and breathed in deep. Genos shivered involuntarily, instincts that had been subdued for years now surging back to the surface.

It reminded him of the first time he'd encountered Saitama, and that puzzled look that had crossed his face. Saitama had scented Genos where he'd lain half broken in the street, huffing out searching breaths against Genos' throat, as if looking for something he could not find. Eyes lit up, a growl lingering in his mouth, hands clutching at the metal of Genos' wrist.

Then he'd pulled back, cocking his head to the side in a disturbingly canine way, brows furrowed at Genos in question. For the briefest of moments, Saitama seemed angry. Like someone had stolen from him, but he could not put his finger on exactly what had been taken. A sense of wrongness he felt but couldn't place. A heaving sigh, a transitory snarl, and the light in Saitama's eyes had faded away, never to be seen again. Until now, his lip curled back from his teeth as he nosed into Genos' glands.

Glands he had not possessed before. Had not thought he needed, had not wanted to wear under the false skin of his throat, or tucked away into his thighs. People looked at omegas, or caught their scent, and their first thought was inevitably 'weak' .

Submissive.

Someone who needed protection. Someone who was not a threat, and Genos did not want those dismissive eyes falling on him before flitting away. Discounting his very existence before they even really looked at him. Genos wanted to be strong .

So when Kuseno had transformed him into a cyborg, cutting away his damaged flesh and replacing it with metal and wires and circuitry, Genos told the doctor to leave out the glands.

Let him be a beta, no one would ever know, and he could live his life without the condescending stares of alphas on him. Kuseno had chided Genos, your brain is still an omega's brain, I don't know how this might affect you later , but Genos held firm.

The loss of his dynamic at such a young age had not affected him at all, really. It was harder to adjust to his new body than it was any loss of omegan instinct. By the time Genos could work the canons in his arms, or operate the analytics that flitted through the corners of his vision, he'd almost forgotten he was an omega at all. Until he met Saitama, that is.

Saitama, who was somehow both more and less alpha than any he had ever encountered. Saitama's strength was unequaled, and he could beat any enemy without breaking a sweat. Destroy buildings without even trying, break open meteors with nothing but his fists. Monsters trembled in his wake, when there was anything left of them to do so, anyway. The other heroes who knew his true power did not even entertain the possibility that they might defeat him.

But he didn't challenge other alphas for dominance. There were no staring contests, no growling matches, no unspoken tension hovering in the air between Saitama and others of his dynamic. It was as though he did not posses the same instincts that sought to subdue and dominate. Saitama walked past omegas without so much as raising his eyes. Even those lost in the rush of their heats did not elicit a second glance from him. They looked at Saitama , to be sure, confused by such an overpowering scent coming from an alpha who appeared docile and unconcerned with them. It was bizarre, and unprecedented, and Genos did not quite know what to think of it. Still, even in its strangeness, it wasn't particularly troubling.

The longer he was around Saitama, though, the stranger Genos himself felt. His neck itched when he sat next to Saitama for too long, heat swelling up where his pulse would have throbbed, had he still possessed such a thing. Genos thighs wanted to squeeze together at the thought of Saitama. His hands on Genos' armor. His thumbs in Genos' mouth. His teeth on Genos' skin. Fuck . He found himself tilting his head sometimes, exposing his throat to Saitama.

Submitting. Presenting .

Which was ridiculous. He was not an omega anymore, not really. Did not produce pheromones, could not go into heat. So why did Genos' eyes sometimes hold Saitama's

before dropping away in submission? Why did his knees want to fall wide in answer to a question the hero had not even asked?

Begging with his body for something he physically could not have. Something Saitama did not want to give to anyone, let alone Genos.

Then Genos' analytics began to glitch. At first it was only in the midst of battle as he strained his cybernetics to the breaking point. His throat would start itching, warmth spreading over Genos like a fog, and then everything went to shit. His targeting systems would shut off, leaving his heat canon firing blind. Vents not wanting open, failing to cool down his internal workings. He'd suffered a thermal shutdown once as they faced a horde of robots, leaving Saitama to finish them off by himself. Another time his neural networks went into overdrive, and even the wind blowing against Genos' plating was enough to bring him to his knees. Genos tried to write it off as an issue with his brain implants. He needed new hardware, new cybernetics, and everything would be fine.

Except it was not, and even after Kuseno put new gear in him, circuitry so advanced it could run an army of cyborgs all on its own, Genos continued to have problems. Not just during firefights, but all the time. That telltale warmth swelled over Genos' skin as he sat next to Saitama one evening, and Genos woke up to find Saitama crouched over him. Face a mask of concern, palms cupping Genos' cheeks as he called out his name.

Genos, Genos, Genos.

Laced with worry. Affectionate, in a way that Saitama rarely was with him. Genos had not glitched, or overheated, or gone into sensory overload.

He'd just shut down completely. No warnings, no error messages, no analytical screens flashing red. Genos turned off like a light switch, only to blink those gold black eyes open at Saitama a few minutes later in confusion.

It happened three more times before Saitama dragged him to Kuseno's, and even then it had taken the threat of violence. Spoken in a voice that sounded bored, but brooked no argument.

'I'll tear your legs off and carry you there, Genos. You're going to get yourself killed.'

Saitama was probably right, but that didn't make Genos any more eager to go see the doctor. Because try as he might to come up with something else, there was only one reason Genos could think of for his systems to start going sideways all at once. His body might not age, but his mind was still human, and he was almost twenty years old.

Most omegas had gone into heat by then. Nineteen was pushing it, and Kuseno had warned Genos this could happen. That his brain might not understand the absence of his glands and organs, and try to throw him into his first cycle. According to Kuseno, there was only one way to fix it.

The doctor put Genos under, and he woke up with all sorts of things he'd rather have been without. Artificial glands in his throat oozing hormones out into his bloodstream. Soft flesh on the upper parts of his legs, more of the glands tucked away beneath it. From his hips to his thighs, on the outside at least, Genos looked totally human. The moment he first opened his eyes, looking up at Kuseno in the confusion of lingering anesthesia, Genos' nose wrinkled in disgust.

He smelled of omega. Was omega, for all intents and purposes. Not that he could reproduce, and thank god for that, but this was bad enough. A scent that screamed weakness, more flesh to protect in battle.

A body that would betray him soon. Throw Genos into a heat, and he'd have to come crawling back to Kuseno's to suffer through it, because even suppressants could not totally quell the ferocity of an omega's first cycle. Kuseno told him he probably had a couple of weeks before things got too serious, his glands needing time to produce the hormones necessary for a heat. Genos had trudged home feeling defeated in a way he never had before. Beaten by his own body, never given a chance for victory. His very DNA conspiring against him, and Genos wanted to bash his face into a wall.

Then he'd come through the door of the apartment he shared with Saitama, and he was in Genos' face in an instant. Inhaling Genos' scent, arm sliding around his back. One hand eased from his jaw and into his hair, fisting in the synthetic strands. Saitama was growling, and when he pulled back to look up at Genos his eyes were still alight. Wide, and full of wonder, looking at Genos like he had done something amazing.

"Genos." Genos' jaw shivered as he tried to find words, head falling to the side, eyes dropping in submission.

As they always had for Saitama, and no one else on earth.

"S-Sensei?" Genos asked, and Saitama breathed in deep again, lips coming back from his teeth. Tongue tracing over them as though they itched to bite into something.

My throat. My thighs. Genos wished, anyway.

"You're an omega ."

"Yes, sensei. Kuseno had to put my glands back. It seems that is why my cybernetics were glitching. I am sorry if this troubles you. I can leave, if I need to, until my hormone levels even out." After his heat sometime, probably, but Genos kept his mouth shut. Saitama's eyes flashed impossibly brighter, another growl easing out of his throat.

"You're not going anywhere, Genos."

Genos was stunned into silence, and after a few moments it seemed like Saitama came back to himself. Dropped his hand from Genos' waist, took a step away from him, shaking his head. Blinking his eyes, like he was trying to bring them back to normal, but they still shone bright and hot.

Throwing out light that danced over Genos, and he wanted to live in that possessive illumination for the rest of his life. Then Saitama stammered out an apology, hands fisted at his sides.

"Sorry. I… I'm sorry." Saitama fled, taking off to the bathroom and slamming the door behind him.

Maybe he was sorry, but Genos was not. He wasn't too sure exactly what had happened between them just then, but the omega inside him that he'd shoved aside for so long was alight with joy.

Savage, and victorious, and even if he had not triumphed over anything that did not seem to matter.

Soon. It would be soon.

Alpha

After that things were much the same, and yet very different. Genos woke up with Saitama's face shoved in his throat most mornings, arms like a vise around him, metal protesting under Saitama's hold. He would roll into Genos' futon again and again, and though he never seemed to catch him doing it, after awhile it was not a surprise. It was more work than he would have expected to ease himself out of Saitama's grasp without disturbing him, but Genos didn't know what else to do. He wasn't ready to deal with whatever expression Saitama might wear should he realize how he clung to Genos at night, growling into his skin. If Saitama noticed he woke up in Genos' futon, nosing into his pillow as though he needed to in order to breathe, Saitama didn't say anything.

They still went about their daily routine as they always had, Genos cooking and cleaning while Saitama lounged around, but now when Genos left the house he never did so alone. Saitama was always ready with some reason he needed to tag along, eyes narrowed on everyone around them. For the first time ever, Genos caught him throwing glares at alphas that strayed too close, and watched them skitter away in fright at the sight of him. If they did not move fast enough, Saitama would growl , a vicious noise that hit Genos somewhere in the tubes of his guts.

Everyone who heard the sound cringed and fled, eager to put as much distance between Saitama and themselves as possible. Everyone except Genos, that is. Saitama's snarling was soothing. Made his eyes fall closed, all the tension easing out of him in a rush, and it was hard for Genos not to move closer to Saitama. To press his face into the rumbling of Saitama's chest. To let his head crane to the side in submission.

To beg shamelessly, please sensei.

Genos held back, even if the effort made him ache somewhere behind his lungs, but he couldn't stop the noise of Saitama's aggression from warming him inside. Neither one of them acknowledged his bizarre new tendencies, dancing carefully around the issue at hand, but Genos knew sooner or later it would come up. Eventually he would be forced to go to Kuseno's to endure his heat, so his scent and desperation didn't torture Saitama for days on end.

It was not a conversation Genos looking forward to having, especially considering the way Saitama reacted before.

"You're not going anywhere, Genos."

Genos didn't want to go anywhere, but he didn't have much choice, either. He couldn't endure a heat with Saitama nearby. Not without pleading for Saitama's touch, and that would be unfair to the him. Maybe Saitama was oddly protective of him now, instincts that had lain dormant rising up in response to Genos' newly exposed dynamic. But that did not necessarily mean he wanted to mate Genos .

Did it?

Genos did not think so, was terrified to let himself hope for something that seemed impossible. The idea of Saitama taking Genos to mate was as tantalizing as it was ridiculous, and he shoved such thoughts out of his mind as quickly as they arose.

Not quickly enough sometimes, it seemed, his scent riling up with lust and drawing Saitama's stare. Eyes flashing white, lingering on Genos in a way that made him rock in place. Hands fisting open and closed, and Saitama would inevitably leave the room to escape him. Genos felt fresh guilt every time, chasing Saitama from his own couch or futon without meaning to. Always an inconvenience, and Genos wondered yet again if Saitama might be better off without him around.

So a week after he returned from Kuseno's, when Genos' cell phone went off to summon him to a meeting at the Hero Association headquarters, he jumped at the chance to give Saitama some space. There were no monsters, no threats looming, no reason for Saitama to tag along, and he always seemed miserable sitting around the table with the other heroes. Bored out of his mind, restless, eager to get away as soon as possible.

Yet when he moved to leave Saitama was right behind him, so close Genos almost tripped over his feet. Genos did not understand why, puzzling over it silently as they made their way to HA headquarters. He did not need someone looking after him, as Saitama well knew. Genos could handle almost any enemy he faced without much struggle, and there were no foes waiting for him at the Hero Association.

There were alphas, though, and when they reached the door that would take them into the meeting room full of heroes, their scent assailed Genos like never before. The new omegan hormones rushing in his veins must have made him more sensitive to the smell, because the essence of all those alphas hit him hard. His nose wrinkled, steps faltering, and he wondered if he could shut off his olfactory sensors altogether for the duration of the meeting. It would be better to smell nothing at all then to be forced to breathe in the scent of so many alphas mingling together. Genos already felt vaguely nauseated, which did not really make sense.

Unmated omegas were supposed to be attracted to an alpha's scent, not repulsed by it.

Genos was braced for the smell to get worse, one hand reaching out to pull open the door, when Saitama stopped him. He grabbed his arm, pulling Genos back a step, grip mercilessly tight on his armor. Genos turned to glance at him, only to find Saitama looking at the ground, teeth bared in a snarl, eyes wrenched shut. When he took a breath Genos watched white flash behind Saitama's lids, and as they opened again he bit back a whine.

Saitama looked feral . Gaze lighting up even brighter as he stared at Genos, head cocked to the side. He threw a vicious glare at the door behind Genos, a growl bubbling up in his throat, and he shook his head back and forth. Blinked his eyes, tried to steady his breathing. Failed at pulling himself together, and Genos found himself worried.

"Sensei?" Saitama flinched at the title, but then his hands were easing up Genos' arms, trailing heat in their wake. Over his shoulders, across his throat, until his palms were splayed out on either side of Genos' neck. Digging into the black skin there, not hard enough to hurt, but there was nothing gentle about it either. He pressed his thumbs into Genos' jaw, forcing his head up slightly, and Genos could smell his own scent pulse thick into the air between them. Wanting, and desperate, asking for things without words, and they filled up his mouth and threatened to spill over when Saitama pinned him with a dark stare.

"I need…" Saitama cringed at his own voice, hesitating before he continued. "I need to scent mark you." Genos felt himself blink stupidly, Saitama's words not quite processing.

"Why?" He blurted it without thinking, everything in him wanting the answer. Genos wished he could pull the word back into himself. Saitama's face twisted up with frustration, but Genos was not the only one who's mouth ran out ahead of him, because Saitama stammered out a response. Frantic, and furious, everything rushing forward at once.

"They'll smell you . You haven't been here since you went to Kuseno's, they don't even know you're an omega! Most of these guys are alphas, and I can't have them-" He cut himself off, flinching again, and took a deep breath before finishing. Looked Genos straight in the eye, trying to say more than his voice ever could. "I need my scent on you, Genos."

Fuck. Fuck .

Please .

For a moment, Genos could not make his lungs work, could not force air past them to make a sound. But even if the rush of lust in his scent was not answer enough, Genos' body knew what to do. Knew what it wanted, and how to get it, and Genos let his head fall to the side, Saitama's hands moving with him. Eyes dropping to the floor, instincts roiling in victory, and finally something shuddered into place inside of Genos. Unlocked his jaw, and loosed his tongue, and when he spoke it tasted like honey.

"Please, sensei."

Saitama growled, something primal and savage that belonged not amongst the skyscrapers of City Z but nestled in ancient forests. A sound that curled through shadows in the night, coiling against the last rays of sunset, swelling over that first burst of starlight.

Saitama shoved into Genos like a ton a bricks, throats sliding together, pushing against him with so much force that he staggered backwards. Saitama's skin was hot on Genos' own, slick with scent, and suddenly it was not just their necks pressed together but all of them. He switched from one side of Genos throat to the other and back again, as if he could not decide which part he wanted to cover in himself. Saitama's heat was everywhere, one of his hands easing into Genos' hair, the other slipping around his back to pull him closer.

His palm flattened over Genos' spine as he drenched him in the smell of alpha, but Saitama's scent did not make his nose wrinkle in disgust. It made his breaths go ragged and uneven, made Genos desperate to drink in as much as he could, to fill his lungs up with Saitama. To keep Saitama inside of him, carry his essence around always, a part of him that belonged only to Genos. Sensei. He moaned as Saitama snarled against his throat, and then his hand

moved lower, fingertips finding the softness that now covered Genos hips. Sensei quaked, hand groping violently at Genos' skin, hungry and frantic, moving down towards the swell of his ass.

Just before he could take a rough handful of Genos' flesh, Saitama threw himself backwards, gasping like a drowning man. He leaned forward, hands on his knees, looking at Genos with wide eyes that wanted to linger at his waist. Accusatory, almost, gaze heavy on Genos' hips, his thighs. Undressing Genos with a glance, trying to stare through his clothes to see what lay beneath. Something he'd not seen before.

Something warm and soft and aching for Saitama's touch.

After a few moments Saitama caught his breath, standing up to his full height, eyes finally dark again. His scent overwhelmed Genos, rolling around him in a fog, and he wondered if his expression looked like Saitama's in that moment. Miles away.

Totally lost.

Then footsteps sounded out from down the hallway, and Genos broke out of his daze and gathered himself.

"We should… ah, go in, sensei. The meeting will start soon." Saitama looked at him strangely, as though he'd spoken a foreign language, and for a moment Genos wondered if he would have to repeat himself. Then Saitama pushed in front of Genos with a nod, one hand on the door knob, and paused.

Saitama stood taller. Lifted his chin high, rolled his shoulders, popped his neck. It did not look like he was heading into a gathering of his allies.

It looked like he was getting ready for battle, and Genos couldn't decide how he should feel.

He was pleased, and terrified, and he followed after Saitama without hesitation.

As he always would.

Dynamic

Saitama stood with his hand on the door for long moments, breathing deep to calm himself, but it only made things worse. With each lungful of air, he took in Genos' scent even further, and it made his mind spin. The smell was both soothing and aggravating at once, and Saitama could not seem to focus on either aspect. Soothing because Saitama had never scented anything in all the world as wonderful as Genos, the pure unfettered scent of his want sweeter than any perfume, more appetizing than any meal. He'd been soaking in it for a week now, surrounded by Genos' sharp essence. It wasn't as though he hadn't enjoyed being around Genos before. Saitama had never felt comfortable with another person the way he did with Genos. There was none of the strain that sometimes came with being near someone, a constant drain on his energy, their very presence exhausting. With Genos there was only calm, and Saitama felt at home with him no matter where they were.

Genos was the place he belonged, more than any apartment in City Z.

Saitama had been fighting the urge to get closer to Genos for a long time. The alpha inside of him was always a bit restless, and Saitama walked around most of the time feeling as though he'd forgotten something. A nagging sensation he couldn't quite shake, even if he knew, deep down, what he was neglecting to do.

Saitama had not marked his mate, or at least the person his inner alpha insisted belonged to them. Genos was theirs , and Saitama's instincts were persistent in telling him so. But Genos' scent did not paint the picture of a willing mate. Didn't paint any picture at all, really.

He was a beta, but he did not smell like one. Genos did not smell like any particular dynamic, but when Saitama had asked if he was a beta, he'd nodded an affirmative. Something like that, he'd said, and Saitama had not pushed further on the subject. He rarely pushed further on any subject, honestly.

Even a beta's smell would be clear enough to indicate their attraction, though, and Genos' scent was always free of any trace of want or desire. Clean, untainted by the things Saitama knew lit him up inside. Or it had been, until a week ago when Genos came home from Dr. Kuseno's laboratory.

Smelling like lust and mate and sunshine and looking at Saitama as though he wanted to be eaten . And fuck, Saitama had zero qualms about obliging Genos, but he had only just gotten his glands replaced after four years without them. What if everything he was feeling was a result of his new omegan hormones and nothing more?

What if it was not Saitama himself Genos wanted, but a strong alpha in general, his instincts yearning to be mated? Maybe it was proximity, Genos spending so much time with Saitama, overrun with needs he could not reign in. But it was getting harder for Saitama to hold onto that logic as the days passed. Genos did not spare the alphas they met in City Z a passing glance. Walked by them as though they didn't exist. Even those alphas who looked at Genos with their eyes lit up, lips bitten between their teeth, gazes wandering up and down him.

Wondering what sort of parts he had, and Saitama would be damned if they ever found out. Snarled at them, and they took one look at Saitama, one whiff of his scent, and fled without fail. Genos ignored them all, but he did not ignore Saitama. Now more than ever he was conscious of Genos, and the way those gold eyes met his and flitted down in passive submission. How Genos' thighs spread, just slightly, when Saitama looked at him for a few moments too long.

The angle of Genos' throat when he titled his head to the side, exposing his glands to Saitama.

Presenting to Saitama without realizing it. Asking for something Saitama was desperate to give, but didn't know how to ask for without giving voice to the possessive sounds that wanted to rise in his mouth. Something he'd never desired before Genos, and Saitama had spent the better part of a week coming to terms with just how aggressively he wanted it now.

How aggressively he wanted Genos , now.

He woke up with his face shoved into Genos' pillow, inhaling that scent of his, the ghost of his warmth lingering on Saitama's skin. That scent that was intoxicating, but driving Saitama insane in more ways than one. With desire, and also with rage.

Saitama wanted to rip apart the alphas in the room before them, and he had not even opened the door. He could scent more than one hero of his own dynamic inside, and the logical part of Saitama knew they would not legitimately go after Genos. For the most part. Of the

alphas in S-Class, Bang was too old, Puri was back in jail, Atomic Samurai was straight. Probably. Saitama assumed, anyway. The only two who might be troublesome were Metal Bat and Zombieman. But Zombieman was not particularly talkative and kept mostly to himself. Saitama could not really picture him getting riled up over Genos and his newly revealed dynamic.

Metal Bat, though. Saitama didn't know what to expect from him. Didn't know him very well, and his lips rose up off his teeth at the thought of the hero looking at Genos. He'd scent marked Genos, and Saitama thought that might be enough to ease some of his hostility. It had not, territorial urges riling up in him, even more viciously than before.

Now all Saitama wanted to do was throw Genos over his shoulder and carry him back home. Toss him down on their futons.

Lay eyes on that soft skin he'd felt hiding under Genos' clothes. Feel it, and taste it, and toy with it. Sink his teeth into the pale synthetic flesh on the inside of Genos' thighs and see if it bruised under his mouth.

Saitama hoped it did.

First he had to get through this meeting without tearing the building apart. Even if an alpha made eyes at Genos, or tried to flirt with him, Saitama really couldn't do anything. For one no one deserved to die just for making a move on an unclaimed omega. Saitama did not think he could get into a fight over Genos and hold back, not with the way his instincts were riling just underneath his skin. If he threw his fists, he would end lives, and probably destroy the Hero Association headquarters in the process. So he needed to stay close to Genos, and focus of the sweet scent he put off mingling with his own. Think of the way Genos presented that pretty black throat for him, and parted those newly soft thighs. How Genos moved closer to him on the couch without realizing, and brushed their fingers together.

The way Genos' voice sounded when he moaned out Saitama's name in his sleep.

Saitama needed to keep calm, and remember that Genos was his, more than anyone else's. Or he would be, soon. If Saitama couldn't keep his cool, well…

Carrying Genos off like a warprize wasn't the worst idea in the world.

So he swallowed down the growl that was on his tongue, and stood up straight. Rolled his shoulders, cracked his jaw.

Remembered what Genos felt like. Genos' face under his hands, his skin soft, his body strong.

Mine , Saitama thought, and pushed the door wide.

Croon

Only about half of the S-Class heroes assembled for the meeting, though considering the gathering was not to address an immediate threat but rather to prepare for future ones, Genos could not really say he was surprised. He'd only gone in order to give Saitama some space, but that plan had backfired in a beautiful way and it would seem strange to back out now. Blast was absent as usual, as well as Metal Knight and S-Class ranks ten, eleven, and twelve. The Child Emperor was nowhere to be seen, and Genos absently wondered if he was in school. Those who had arrived before Saitama and Genos glanced their way as they came through the door, King waving and Bang opening his mouth to greet the pair, but it was Tatsumaki who spoke first.

It was always, always Tatsumaki.

She moved towards the door and blocked their path, hovering just above Genos and Saitama with her arms crossed, a glare etched in place on her face.

"Cyborg! You brought this useless no-class hero again? He's got no business in an S-Class meeting! You should know better by now! Both of you might as well leave, you're no use to us anyway. If there's a threat I'll handle it, you-"

She stopped talking abruptly, nostrils flaring, breathing in deep. Tatsumaki was a beta, and their noses were nowhere near as sensitive as an alpha or omega's nose, but it was still only a moment or two before she caught their scents. Genos' scent, undeniably omega where it had not been before, Saitama's laced so heavily with Genos' that there could be no mistaking why. Anyone would be able to tell Genos had been scent marked, no matter their dynamic. Her eyes went wide, mouth falling open, and she suddenly looked vaguely disgusted.

"Unbelievable. You're an omega, and you let this guy scent mark you? What kind of parts do you have under there, metal head? Cyborgs can't reproduce, can they? I hope you can't, because-"

Saitama growled, and every hero in the room who'd been tuning out Tatsumaki turned at the sound. Saitama stood in front of Genos, eyes flashing white at Tatsumaki, hands clenched tight into fists.

"His 'parts' are not your concern."

The words were quiet enough that only Tatsumaki could hear, but everyone felt the aggression in Saitama's growl. Not just a sound they heard, but vibrations that rattled deep in their chests, something instinctive telling them to be wary. Whispering threat , even if they did not want to acknowledge another alpha as such. The Hero Association meetings were often rife with conflict, that was nothing new. There was posturing and snarling and lots of staring contests to establish dominance. Shoving and hissing and territorial displays. Put so many alphas in a room together and it was bound to happen.

But it had never come from Saitama .

The silence was heavy for a moment, and then Genos could hear the alphas in the room scenting the air, their soft sniffing noises echoing in the background. Scenting me , Genos realized, and the idea of so many alpha's taking in his omegan scent would have bothered him four years ago. Made him feel weak and insignificant.

But now it was twined with Saitama's, an undisputable claim, and Genos couldn't help but feel proud . Any omega would, had Saitama been their alpha. Mine , Genos thought.

He's mine .

Tatsumaki was about to speak again only to be interrupted by Bang, voice wry and amused as he made his way over to them.

"If you're going to fight each other you should wait until after the meeting. I don't really feel like climbing out of the rubble of headquarters after you two tear it down. Charanko's making curry tonight."

Tatsumaki made an offended, indignant sound, like the very idea of fighting Saitama was beneath her, but she muttered insults under her breath even as she returned to her seat. Everyone was talking in low voices, and Genos could've picked it out if he wanted to, but it

didn't seem important. He didn't care what these people thought of them. Nothing could be more irrelevant to Genos. Bang stood next to them, patting Saitama on the shoulder but wisely refraining from greeting Genos the same way as he might have once. He nodded at him instead, a smile creeping over his features.

"I guess congratulations are in order." Saitama did not speak, and when Genos glanced at him he seemed to be gritting his teeth.

Trying not to growl at Bang when he'd done nothing wrong, other than stand a little too close for Saitama's liking and grin at Genos. The idea that Saitama was so possessive of him warmed Genos inside, and he fought a smile off his face. Genos waved away Bang's pleasantries, unsure how Saitama might react to them.

"Congratulations are not necessary." Bang laughed then, taking a generous step back as Saitama's scent surged up stronger in the air. Aggressive, and challenging, but Bang did not really seem bothered.

"I don't mean for you! I mean for me! I just won a bet, King owes us all dinner soon." Genos cocked his head, still standing behind Saitama, unwilling to test his control by moving forward.

"A bet?" Bang nodded at the Genos' words, turning to head back to his seat as he replied.

"Well, I didn't really expect you'd show up one day smelling like an omega, but I knew sooner or later Saitama would put his mark on you. Better sit down and get this over with so we can all get out of here. Before Saitama tears the place down!"

Bang cackled at his own joke, reaching over Atomic Samurai when he sat down in order to shove at King. Trying to make sure the beta knew he'd lost, in case Genos' scent had not reached him yet. Genos and Saitama took their own seats, Saitama positioning himself between Genos and Metal Bat. Saitama caught the hero's gaze and held it, chin raised high, challenging Bat without words. Metal Bat just smirked, letting his eyes fall away, not game to try and fight Saitama for dominance. He twirled his bat, putting his feet up on the table in front of him and making a derisive noise.

"Relax, baldy, nobody wants ta stick their dick in your tin can of an omega."

Saitama hissed and turned towards Metal Bat, too fast to be anything but violent, only to be stilled by Genos' hand on his shoulder. Saitama froze instantly, as though Genos had pressed a button and turned off Saitama's attack. He looked back at Genos, eyes bright with hostility, though Genos knew it wasn't directed at him. Genos leaned in close, speaking low so no one else would hear.

"If you wish to fight half of S-Class I will help you, sensei. I am sure we would win. But I will likely have to go for repairs, and it will be difficult for me to help you fight the rest of the Hero Association when they come for us. You will have to handle them on your own. Especially considering that I will be going into heat in a week or so."

The noise that came out of Saitama was obscene , a deep rumbling that was unlike anything Genos had ever heard before.

Saitama was crooning to him. In the middle of the Hero Association, where anyone could hear. An alpha's croon was at home in slick stained sheets, in the wet air near hungry mouths and warm skin, with the scent of lust and want riling between mates. The music of a heat, an alpha's love for their omega pouring out because they could no longer contain it. It said more than words ever could, drawn out by instinct instead of thought.

I love you, I need you, I want you. You're safe. You're perfect. You're mine.

Genos knew, without a doubt, that Saitama had not meant to croon. He also knew there was no feigning the sound, no forcing it, no rushing it. It happened or it didn't, only the strength of an alpha's feelings holding any sway in the matter.

Saitama loved him. Saitama needed him.

Saitama would fight every hero there, for no reason at all, just for looking at Genos wrong. For insulting him.

Standing too close to him, or breathing his scent too deeply.

Genos' eyes fell closed, and he laid his forehead on Saitama's shoulder, shuddering when Saitama's fingers came up to thread through his hair. Saitama nuzzled into the strands, lips pulled up from his teeth. He still did not seem to be aware of the noise he was making, or of all the eyes on them, everyone staring with blatant disbelief. Genos could feel them looking, but he could not find it in himself to care. He'd gone to the meeting because he thought Saitama needed space, but Genos had been wrong.

Saitama did not want space.

Saitama wanted Genos.

"S-sensei, let's go home."

"Please do, no one wants to listen to that disgusting display," Tatsumaki hissed, but Genos wasn't listening to her.

Saitama stood up and grabbed Genos by the arm, dragging him from the room as though he might resist. As though he'd ever wanted to do anything besides follow after Saitama. They took the stairs down to the ground floor, Saitama tugging him all the while. His croon had finally ceased, and once they got outside he crouched down in front of Genos, presenting his back to him.

"Climb on." Genos eyed him strangely, brows furrowed.

"Sensei?" Saitama looked at Genos from over his shoulder, exasperated but bright eyed with emotion.

Just as overwhelmed as Genos, and he was glad for that.

"It's this, or I carry you princess style all the way back home, Genos. Your choice."

Genos took in a shaky breath. Saitama had carried Genos like this many times, but he'd always been injured. Missing his legs, unable to walk to Kuseno's for repair.

He climbed onto Saitama's back, whole in ways he'd never been before. Covered in his alpha's scent, Saitama's muscles strong underneath his plating. In that moment he understood why Saitama had insisted on carrying him. He needed the contact, too, needed to feel Saitama against every inch of him. Saitama started walking, picking up a deliberately normal pace, and Genos nuzzled his face into Saitama's throat. Pressed a soft little kiss underneath Saitama's ear, breathing him in, nosing at his glands.

Saitama's grip went brutal on Genos' thighs, and if he hadn't possessed supernaturally keen ears, he would have missed the words.

Just wait until I get you home.

Sharp

When Saitama brought him into their apartment, Genos expected to be pinned against a wall. Shoved onto the kitchen counter, splayed out over the kotatsu. The whole way home he'd been pressed up against Saitama, his scent riling in Genos' nose, stronger with every step. Not just his individual scent, the one that Genos had grown used to breathing in deep at night when Saitama eased close, but a different smell entirely. One full of lust and desire, and with the memory of Saitama's croon still echoing in his ears, Genos could feel himself growing heated and needy.

Could feel himself slicking in readiness, and Genos would have been embarrassed if he hadn't been aware of the exact moment Saitama caught the scent of it. He inhaled sharply, then stopped walking for a moment and shuddered hard, fingers so tight on Genos' thighs that the metal whined beneath them. The growl that came out of him was loud enough that an alpha across the street turned to look at them before scurrying off down the road. Away from Saitama, and the feral violence promised by his bared teeth and brutal noise. Noise that had Genos whimpering in answer, an omega's cry pouring out of his throat unbidden to plead for that violence to be laid out against his flesh.

After miles and miles of barely leashed aggression, Genos was anticipating Saitama's lips on his as soon as the door closed them off from the rest of the world. It would be brutal, and desperate, and full of the raw emotion Genos could scent in the air, could taste in his mouth when he pressed it teasingly just beneath Saitama's ear. And Genos was so fucking ready , but the rough kiss he waited for didn't come.

Instead Saitama eased him down to his feet, and then headed into the living room like Genos wasn't even there to lay their futons out side by side. Saitama put the sheets and blankets on them, positioning the pillows next to each other in the center, folding the heart patterned comforter back. He was bizarrely calm considering the smells of rut he was putting off, the light shining out from his eyes, the air he was desperately sucking into his lungs. As though he was in the midst of a fight, as opposed to making a bed with trembling hands.

Then he made his way back over to Genos, and Saitama ate him alive with his eyes. From head to toe and back again, gaze flashing brighter and brighter until it was almost too much to look at.

Still, Genos couldn't look away. Would stare until his eyes burned out, probably, if it meant the last thing he saw was Saitama.

Saitama took a step closer, almost chest to chest with Genos, and met his stare with a pleading expression. Genos watched his jaw flex, Saitama's hands clenching into tight fists before he took a deep breath.

"Can I touch you, Genos?"

There were not enough languages on earth to adequately tell Saitama just how much Genos wanted to be touched by him. His mouth wasn't working, really, despite having fallen open in the attempt to form a reply. Genos made a sound in answer instead, though it wasn't anything intelligible. Just another omegan whine, all instinct and no words, but along with the fervent nod he gave it must have been enough.

Because then Saitama's hands were on him, jerking Genos' shirt off over his head in rough motions to lay his plating bare. The floor vanished beneath his feet, and Saitama's palms spread out under Genos' thighs, lifting him into the air effortlessly. A moment later he was on his back on their futons, Saitama settling between his legs as though he'd always been there. His fingers coiling in Genos hair, his hips nestled against Genos own.

Like he'd been formed from smoke and ether just to lay down on top of him and nudge Genos' knees apart. To trail his hands up Genos' sides.

To swallow him whole with a hunger that Genos longed to be consumed by.

Saitama leaned in close to Genos' face, one hand cupping his cheek reverently, thumb playing back and forth over his bottom lip. Inches apart, the heat of his breath fanning out over Genos' mouth, bright eyed and needful and so fucking beautiful.

"Can I kiss you, Genos?" Genos heaved out an exhale, thighs thrown impossibly wider, back arching as he tilted his head to the side in submission.

"You can do anything you want to me, sensei."

Saitama shook against him, dark guttural noises rising in his throat, and then he brought their lips together and Genos was broken. His mind, his body, none of it functioning anymore except to go limp and loose and yielding. There was only Saitama's hand in Genos' hair, his weight holding Genos' down, Saitama's mouth pressed against his. His wet tongue spilling into Genos' lips, and he parted them eagerly, letting himself be devoured by Saitama's kiss.

Saitama was kissing him , and touching him , and rutting mindlessly against him. Genos couldn't have bitten back the whimpering sounds he was making if he'd tried, not that he wanted to. Saitama needed to hear, needed to know that Genos was lost to him. He felt Saitama grinding down into his arousal, along with the moisture that soaked through his boxers, through his jeans. It was obscene, how wet he was for Saitama, and Genos took his hand into his own, pressing Saitama's fingers to the ruined fabric of his clothes.

Saitama hissed into Genos' lips, palming at his jeans, graceless and rough. He didn't stop kissing Genos, but trailed his mouth down to Genos' neck to suck viciously at his scent gland. If his neck had not been black, there would have been teeth marks and bruises dancing over his skin, and Genos briefly mourned the loss of them. Saitama clawed Genos' pants open, the button flying off in his haste, and shoved them down past Genos' thighs. When his skin was laid bare Saitama wasted no time, closing a hand around Genos' cock, teeth scraping into his scent gland again before he pulled away to look down.

And froze, eyes locked between Genos legs, spellbound and silent. He worked Genos' jeans the rest of the way off, ignoring the blush on Genos' cheeks, and then Saitama eased back to press his thighs wider and stare.

" Genos ."

Genos knew what he was seeing, even if it didn't seem worthy of the worshipful gaze that painted Saitama's face. There was skin from his hips to just above his knees, the same shade as his face, and he could almost feel Saitama's eyes on it. His cock was hard, curving up towards his stomach, leaking furiously onto the metal of his armor. Then below his throbbing shaft was not a sack, as male alphas and betas had… but the lush pink slit of an omega, pulsing and wet and shining with slick. Saitama stared at him, awestruck, running the backs of his knuckles teasingly over the base of Genos' cock, at the little vestigial nub of his clit.

Just a tiny bump, barely there before it shifted to form the rest of his shaft. He shivered hard at the light touch, a surge of fluid leaking out of him, and wailed out a pitiful little mewl.

"Genos you… you have…" He trailed off, and Genos realized he was surprised to find Genos so fully endowed. But Dr. Kuseno was nothing if not thorough, and he would not have left Genos wanting in any aspect of his design.

"Everything a male omega is meant to have, sensei." Saitama brushed his fingers across Genos sensitive skin, pulling his lips apart ever so slightly, his other hand closing idly over Genos' cock.

"Is it okay? I mean… Can I-" Genos caught Saitama's hand, folding his fingers back until just two of them were outstretched.

Then Genos pressed those fingers into his aching pussy, quaking at the sensation, watching Saitama's jaw shudder.

"I'm yours, Saitama. Please."

Something shattered in Saitama then, and all of his self control was miles away, lost in the wash of a need long denied. He fell between Genos' legs to mouth ravenously at his clit, fingers working within his tight heat. Saitama's other hand stroked Genos' cock, and he could not keep back the moans that poured out of him.

Genos sobbed out Saitama's name, tangled up with pleas and profanities and sensei, sensei … He wasn't sure if Saitama knew what he was doing, or if he was just desperate and wanting, but Genos was fucking shaking . His legs wrapped themselves around Saitama's back, heels digging in to press him closer, thighs trembling under the strain of ecstasy. Genos clutched blindly at Saitama's shoulders, one hand fisting uselessly in the pillow beside his head. He writhed beneath Saitama's mouth, something heated and overwhelming swelling up in his guts. Something new, and powerful, but not frightening.

Because it was Saitama between his legs, tearing him apart, and Genos could do nothing but submit.

Genos had never been touched this way. Before he'd become a cyborg he'd never even been kissed, let alone eaten out and stroked and fucked open on someone's fingers. He'd been worried that Saitama wouldn't be attracted to him, to how completely omega his biology was.

But Saitama was an alpha even if he hadn't always acted like it, and Genos should have known better.

Saitama's tongue swirled mercilessly over his clit, and his hand worked Genos' cock expertly, thumb circling his sensitive crown. His fingers twisted inside Genos just right, and he was already on the edge of orgasm, his virgin slit and swollen cock overstimulated in the best ways.

Then Saitama started crooning into his clit, vibrations running straight through Genos, setting him alight.

"Sensei!"

Genos came hard , seed erupting out over his plating, his cunt going tight and messy around Saitama's fingers as he dripped fresh slick over them. Saitama worked him through the high, finally easing his hands out of Genos when he started pulling away from the touch. He prowled up Genos body, holding his golden stare as he lifted his fingers to his lips and sucked them into his mouth, picking up his croon again. He licked Genos' wetness off of them slowly, and when he was finished, Saitama kissed him hard.

Genos shuddered, tasting himself on Saitama's tongue, melting under the vibrations of Saitama's croon on his lips. Saitama whispered in between kisses, and Genos would remember those words for the rest of his life.

"Genos, you're fucking delicious ."

Genos whined, juncture of his thighs throbbing at the sound of Saitama's voice, and he broke their kiss to tilt his head to the side in submission. He scraped his nails over his gland,

making his scent swell fiercely in the air, and when Saitama met his eyes he smiled.

"Mark me, sensei."

Teeth

Chapter Notes

See the end of the chapter for notes

There was a long moment of stillness, Saitama staring at Genos through alpha bright eyes, nothing lucid about his gaze. As though he was in a trance, lost in a fog of instinct. Then he sank his fingers into Genos' hair, and eased his head further to the side. Genos yielded, craning his neck as far as he could, until the metal of his shoulder was digging into Saitama's knuckles. Saitama lifted his free hand and laid it over Genos' scent glands, synthetic yet no less real, no less vital. His fingertips felt calloused against Genos' skin, rough from Saitama's training, but the touch was reverent.

"Can I?" he asked, blinking like he was trying to come back to himself, and Genos wasn't sure what he meant. If he was seeking permission, or questioning Genos about his biology.

Despite the fact that he'd asked for it, he didn't think Saitama could physically mark him, didn't think the black skin of his throat was capable of taking and holding an alpha's claim.

Genos had learned about the physiology of it in school like everyone else, the hormone interactions and salival enzymes and endorphin responses. The nuance of psychosomatic bonding, and how it shifted into something concrete over time— with contact, with closeness. Neural pathway growth, and pheromone sensitivity, the countless biological processes involved in the formation and nurturing of a mating bite, but that was with normal omegas. Kuseno was skilled, but Genos wasn't sure how far his science stretched, or if he'd even considered that it was something Genos might want. To wear Saitama's teeth in his skin.

To keep them there, always.

Genos didn't think Saitama could mark him, but fuck, but he wanted him to try.

"Please, I want you to. I need it," Genos said, clinging to Saitama, hands fisting in his shirt. Genos tugged at the fabric, felt it tear under his fingers, but couldn't find it in himself to care. "Take- take this off."

It didn't come off like a request, but bossy, command written in the tone. Saitama obeyed without hesitation, releasing Genos for long enough to pull the shirt over his head and toss it away. Then his hands were back, one cupping Genos' head, his other arm wrapping around Genos to pull him closer.

"You sure, Genos?" Saitama asked as he nuzzled into Genos' throat, licking over his glands, that low rumble sounding out again. As though he couldn't help it, couldn't stop crooning.

Asking if he could mark Genos, like it was something of consequence.

As though Genos wasn't broken, an omega cobbled together from wires and tubes and metal, a pitiful imitation of the real thing.

As though it meant something, and Genos whined impatiently, writhing beneath Saitama's weight.

"Please," he said, reaching up to hold Saitama's face tight against his neck, "do it. I want you. I- I love you, sensei."

The timing was probably bad, but it was all he could give Saitama in return, the only answer he had for the drugging euphoria of Saitama's croon. It said more than words ever could, and Genos would answer it in any way he was able. With his words, with the call of his scent and the rush of his slick.

With his body, Genos begging for Saitama with everything in him.

Saitama's growl went guttural as his hips ground forward into Genos, the denim of Saitama's jeans rough against his oversensitive cock.

"Say it- say it again, Genos," Saitama said, words whispered into Genos' throat, lips moving against his skin. "Say my name."

It sounded weak, sounded vulnerable, and Genos let out a shaky breath, because nothing, nothing could hurt Saitama.

Nothing except Genos, Saitama holding his breath and waiting, fragile like he'd never been.

"I love you, Saitama."

A possessive snarl, Saitama's eyes flashing even brighter, and then his teeth sank into Genos' neck. There was a brief stinging sensation, but it didn't register the same way damage to his body normally did, didn't set off his pain receptors. There were no warnings strobing in the corner of his vision, no analytics firing up to keep Genos safe. It just felt good, the way Saitama's touch felt good, the way his hands and his lips and his tongue felt good. Saitama's jaw closed tighter on Genos' glands, biting down harder, and his body lit up everywhere at once.

Fresh slick dripped over the inside of his thighs as his cock throbbed, knees falling wide in invitation. He felt abruptly empty, achingly so, and Genos pawed blindly for Saitama's hand. He pulled it out of his hair and shoved it between his legs, pressing Saitama's fingers into himself, into the wet heat of his slit.

"I don't want to wait for my cycle to hit. I need you now."

It didn't take much coaxing before Saitama was working his fingers deeper into Genos, burying them down to the knuckle, thumb rubbing at the nub of his clit. He released his bite slowly, like it was painful to let go. Saitama sucked and laved at the spot, instincts probably driving him to continue until he left a bruise, until he could see the inky purple work of his mouth on Genos' throat. It was never going to happen, not on the dark synthetic flesh there, but it still had Genos quaking with want as Saitama licked and nipped over his glands. He fucked himself down on Saitama's fingers, wishing it was his cock.

Desperate for the thick swell of Saitama's knot in him, spreading him open, and Genos mewled at the thought because that's what he needed. What he'd needed since he woke up on Kuseno's table, his own scent thick in his nose, warmth already rising in him.

What he was made for, to take all of Saitama and hold him fast.

Saitama kept fingering him, and the sound of it was obscene. It mingled with Genos' breathy little whines, and Saitama's rumbling croon, loud in the eerie hush of their apartment. Filled up the shadows of it, the trappings of them both. Video game cases, manga scattered in one corner, Genos' notebooks stacked on the table beside the computer. Their clothes piled together in the hamper, Genos' extra parts and hardware stacked in the bottom of the closet next to Saitama's shoes.

Their lives irretrievably entwined, impossible to unravel, and Genos reached down to palm Saitama through his jeans, groaning at the feel of him.

"Fuck me, sensei," Genos said without thinking, and Saitama shuddered against him .

His free hand roved over Genos' armor, fingers dipping into vents and tracing plates, clutching and petting and stroking. Worshipful, like Genos was something precious, and when he spoke it was punched out and ragged.

"Genos, fuck. I'm- we don't have to, I... Are you-"

Saitama sounded like he was about to ask Genos for permission again. If he was ready, if he was sure, did he want to wait.

But Genos had been ready for months. Had never been more sure of anything in his life.

Was tired of waiting. He wanted Saitama, wanted him now, instincts making him brave in new ways.

Genos slid his hand into Saitama's jeans, into his boxers, hand closing around his cock. It was thick in his hand, heavy and hot. Rock hard, sticky with precome, the base already

swollen. It wasn't a knot, not yet, but the promise of one, and Genos tightened his fist around it and watched Saitama shake.

"Need your knot. Saitama, please."

Saitama looked wrecked, more fluid leaking out of his cock as Genos squeezed and kneaded, milking it from his crown with greedy fingers.

He was ready to beg, to plead for Saitama, but Genos' didn't have a chance to get more words out. Saitama swore as he sat up on his heels, still twisting his fingers artfully within Genos', and fumbled his jeans open with his free hand. He dislodged Genos' groping touch in the process, but it seemed a small price to pay for what he was getting in return. Only when he had his cock free of his clothes did Saitama withdraw his fingers from Genos', fluid dripping all the way down to his wrist. Drenched already, but Saitama ran his palm over the messy insides of Genos' thighs, gathering more of the liquid that had pooled there.

Then he used it to slick up his cock, Genos' wetness shining on his skin in the muted light, until Saitama was filthy with it. The smell was overwhelming, now, the sugary scent of Genos' want coiling with Saitama's sharper alpha tones to make something new. The scent of an omega, claimed and marked and taken.

Something everyone would smell on him for days, everywhere he went.

Something they would smell on him always, the two of them coiled together, because Genos was never letting Saitama go.

He nudged the head of his cock against Genos' slit, rubbing it gently up and down, easing it between his lips. To make sure Genos' was wet enough, probably, but it just felt like a tease, and the sound Genos' made was pure omegan need given voice. High, and reedy, and inhuman. Not robotic, the way his voice glitched sometimes when he was damaged or drained.

An animal sound, ancient and without language, and Saitama's crooning picked back up as he pressed slowly into Genos' aching cunt. Genos' cry cut off abruptly, Saitama filling him up

inch by inch, until he was trembling. More, and more, the thick base pushing in, too, opening him up even further. Genos' cock was pressed tight between his plating and Saitama's stomach, and the friction was enough to have him gasping. His eyelids fluttered, and he clutched at Saitama's shoulders, at his biceps, unable to breathe through the feeling. Unable to think, unable to speak.

Genos could only be, Saitama pinning Genos in place with his body, palms sliding up his neck to cradle his face.

"Genos," Saitama whispered, so adoring that it hurt Genos' chest, and then brought their mouths together.

He pulled out as their tongues twisted together, the slide of Saitama's cock in him effortless, the stretch perfect. Pushed back in again, licking gingerly into Genos' mouth. It was tentative, like he hadn't already kissed Genos, hadn't already eaten him out and fingered him open. Like Saitama had waited all his life to taste Genos, and wanted to savor it.

The kiss was soft, and careful, and sweet.

Everything Saitama wasn't when he broke their mouths apart and started moving again. He wrapped one arm around the small of Genos' back, using it as leverage to tug Genos' down on his cock and rut in deep. His other palm was splayed out on the floor, supporting his weight as he pistoned forward again and again. Genos couldn't get his limbs to obey him, couldn't get his body to do anything but go limp and let Saitama take him. When he managed to pry his eyes open and look down Saitama's gaze was unearthly bright, stare locked on where he was disappearing into Genos.

His thrusts were brutal, the pace relentless, their bedding coming loose from the futon underneath them as Saitama fucked Genos off their mattresses and onto the floor. Some of the sheets came with them, tangling in Genos' legs, a mess of fabric and denim and metal. Genos' couldn't focus on it, couldn't focus on anything but the way Saitama was filling him — the way heat pooled in him, swirled higher, and Genos felt like he might break.

Saitama slowed after a while, though his movements felt no less desperate. Instead of pulling out and shoving back in hard Saitama was grinding into him, short little jerks of his hips, and it took Genos a few stuttering, frantic strokes to realize why.

His knot was swelling, wider and wider, catching on the tight clench of Genos' walls. Saitama seemed to notice, too, glancing uncertainly at Genos, the white of his eyes dimming slightly as he tried to come back to himself. Tried to blink through the overwhelming instinct to knot, and mark, and own.

To find the man buried underneath the alpha, except it wasn't necessary.

Genos wanted them both.

"Genos, I'm- I'm gonna-"

"Do it," Genos said, heels digging into Saitama's back to hold him in place, "knot me, I want it. Saitama, please."

Then there was nothing but heat, and light, Saitama's knot filling up all at once, come pulsing into Genos' cunt in scorching bursts. There was nowhere for it to go, Saitama's knot keeping it firmly in place, and it soothed an itch Genos hadn't realized he had. A need he hadn't been aware of, to be full of Saitama in every possible way, and something snapped in him. Shattered, and fell away, and he came hard— around Saitama's knot, his walls twitching and clinging, but also onto their stomachs, Genos' cock jerking out ropes of white. It smeared over the metal of his armor, streaked messy across Saitama's abdomen, the smell of it sharp to Genos' over-sensitive receptors.

A few more deep, grinding thrusts, and Saitama finally stilled. He nosed into Genos' throat, breathing hard, but it didn't seem to be from exertion.

He was scenting the air, scenting Genos, and Saitama laid down on top of him until every inch of them was pressed together. Genos could still feel pulses of come erupting into him, weaker than before, but enough to make him whine in bliss. Every little movement, every breath he took tugged on Saitama's knot where they were tied together. Saitama trailed his lips up Genos' neck and over his jaw, stroked fingers through his tangled hair.

"You should have said something sooner. Have you always wanted this?" Saitama asked, kissing Genos in between words.

Genos slid his hands down, wrapping his hand around the base of Saitama's cock as far as he could, feeling where they were connected. It was obscenely wet, hotter than the rest of Saitama's skin, and he shivered hard at the touch. Genos shook his head, tightening his grip on the swell of Saitama's knot, what little he could reach of it.

"Not always this," Genos said, laying his other palm flat on Saitama's chest, on the steady beat on his heart, "but always you."

Saitama growled, collapsing further down against Genos, as though to keep him still. It was too warm, hard to breathe through the press of Saitama's bulk, joints of his hips twisted at an odd angle. Saitama's knot pulled at Genos sex, not painful, but everything felt raw and sensitive. It was already overwhelming, even without the urgent call of his heat driving him relentlessly to seek more, harder, faster, deeper.

Genos opened his vents, letting out puffs of steam to cool himself. Adjusted his neural receptors as best he could, forcing away the worst of the ache, artificial though it might be. Shifted his legs, settling in for the duration of Saitama's knot, unsure of how long it would take to release. Fifteen minutes, up to an hour, but Genos didn't care.

Saitama's mouth was buried in his throat, and his hands were in Genos' hair, bodies bound together. And Genos…

Genos wasn't going anywhere.

Chapter End Notes

A long time coming, but we're finally here. A couple of my readers have been so fucking supportive of me in every way imaginable, and I hope that they enjoy reading this as much as I enjoyed finally, finally getting it done.

/blows kisses to the genosais

I'm sorry it took so long, but better late than never, and I love you.

Works inspired by this one

Please drop by the Archive and comment to let the creator know if you enjoyed their /works/6184534/comments/new